1. Field of the Invention
The present invention relates to the diary industry and provides new diary products in the form of direct consumption fermented milk or as a product of instantaneous reconstitution, such as in concentrated fermented milk and fermented milk powder, having an extended shelf life, the products resulting from the culture in symbiosis of specific bacterias in a substrate comprising milk, whole milk, skim milk, lactosefree milk, etc.
2. Description of the Prior Art
The diary industry has experienced deep changes, therefore it is not only of interest to provide the market with supply natural milk or to process the milk in order to offer its traditional derivatives: cheese, yogurt, etc., but the diary industry's evolution allows that other products and milk derivatives are today available. An important innovation was produced when diary products were offered for the purpose of modifying and improving dietary habits and correcting deficient status in human health conditions, mainly of those who depend on the intestinal bacterial flora or on ingestion of vitamins, minerals (calcium, phosphorous, iron). In this regard, the diary industry has developed and proposed diary products derived from the treatment of milk with lactic bacteria, compatible with the nutritional demand of the modern consumer market.
The satisfaction of these biological demands (and also the market's) has introduced various innovations, such as yogurt and whole or skim milk, products combined with fruits or with cereal milks (soya, sunflower) and also cultured milk, acidophile milk, fermented milk, etc.
To obtain these fermented products, it is of vital importance, in regard to the activity and probiotic (nutritional) capacity of the products, the characteristics of the lactic strains utilized, requirement which obliges to be extremely careful about the relationship between lactic strains.
This demand has promoted the search for new lactic strains, capable of generating lactic based products with probiotic properties (prevention-control-correction of diarrehoeic processes, activation of the immunologic system, prevention of hyper-cholesterolemia, etc.)
It has recently been realized that it is possible to have available new diary products--particularly fermented milks and derivatives of same--including varieties of concentrated and dehydrated (or powder) fermented milk of immediate reconstitution, by growing simultaneous cultures in the same medium of Lactobacillus Casei CRL 341 (ATCC 55544) and Lactobacillus Acidophilus CRL 730 (ATCC 55543). They are two symbiotic lactic strains, so that the symbiotic results in the attainment of biologically active fermented milk products, mainly as a result of the population of viable cells developed in the range of not less than 10.sup.6 to 10.sup.9 CFU/ml.
It is known to provide milk products fermented by inoculation of culture cells, particularly cells of Lactobacillus Casei and Lactobacillus Acidophilus.
This is disclosed in Gonzales et al. (Microbiologie, Ailments, Nutritions 8(4): 349-354, 1990), Perdigon et al. (J. Dairy res. 57(2): 255-264, May 1990), Perdigon et al. (Foods, Nutrition, and Immunity: effects of dairy and fermented milk products. Paubert-Braquet eds., 1992, p66-76), Patel et al. (Indian J. Dairy Sci. 14(7): 379-382, 1992) or Nader de Macias et al. (J. Applied Bacteriology 73(5): 407-411, November 1992).
Gonzales et al. teaches the preparation of a fermented milk product characterized by inoculating skim milk (i.e., a milk substrate) with a viable culture of Lactobacillus Casei and Lactobacillus Acidophilus wherein the microorganisms are at a final concentration of 10.sup.7 to 10.sup.8 cell/ml. Gonzales et al. also suggest the use of this cultured milk to alleviate diarrhea. Perdigon et al. (1990) and Perdigon et al. (1992) teach a fermented milk product containing a mixed culture of Lactobacillus Casei and Lactobacillus Acidophilus and the ability of this fermented milk product to boost the immune system. Patel et al. describes a fermented milk containing 5.times.10.sup.7 viable cells of lactobacilli/ml having the strains Lactobacillus Casei and Lactobacillus Acidophilus. Nader de Macias et al. teaches a milk fermented product containing a mixture of Lactobacillus Casei and Lactobacillus Acidophilus. When fermented milk is prepared using the methods of the cited references, however, it has a short shelf life, e.g., a maximum of 7 days.
In addition, when the fermented milk is prepared using the methods described in the prior cited references, the Lactobacilli continue to produce lactic acid. Higher concentrations of lactic acid render the milk product inedible. It would be therefore very desirable to find a milk product that maintain the drinkable nature of the fermented milk product for longer periods of time, such as 30-60 days in liquid form or 4-6 months in powder form.